Characterization of Low‐Velocity Impact Damage Modes and Correlation Analysis With Damage Mechanisms in Composites Based on Multi‐Source Monitoring Methods

ABSTRACT This study systematically investigates the damage evolution mechanism of carbon fiber reinforced polymer (CFRP) composites under multi‐level impact energies using an integrated approach that combines acoustic emission (AE), infrared thermography (IRT), and digital image correlation (DIC). Three distinct stages were first identified from the impact force response, and the effect of impact energy on characteristic parameters for each stage was quantified. The resulting damage morphology was characterized using ultrasonic C‐scan and scanning electron microscopy (SEM). The dynamic response during impact was then extracted through AE pattern recognition, dynamic IRT field tracking, and full‐field DIC strain analysis. A novel synchronized “AE‐IRT‐DIC” framework was established, capable of correlating elastic wave, thermal, and optical data for coordinated damage monitoring. Key findings reveal that the energy absorption reaches a non‐monotonic minimum at the barely visible impact damage energy ( E BVID ). At 1.5 E BVID , energy dissipation shifts dominantly from elastic waves to thermal radiation and plastic deformation. The damage modes evolve stage‐wise, with IRT features progressing from flocculent patterns to elliptical spots and finally to dendritic networks. A transition from intra‐laminar shear to inter‐laminar delamination occurs at 2 E BVID . The best fitting equations for impact energy versus total AE energy, maximum infrared radiation difference, and maximum strain are the polynomial ( R 2 = 0.985), logistic ( R 2 = 0.999), and exponential ( R 2 = 0.974) functions, respectively. This research provides fundamental insights into the CFRP damage evolution mechanism and critical guidance for designing high‐performance, impact‐resistant composite structures.